Hidden spot on hard drives?

Gary W. Swearingen garys at opusnet.com
Wed Oct 5 17:37:57 PDT 2005


Jonathon McKitrick <jcm at FreeBSD-uk.eu.org> writes:

> 1.  Any idea where this info could be stored?

The obvious place is the end of the first track between the boot
sector(s) and the first partition.  But that's probably too easy and
well-known.  As others have noted, Unix (eg, "dd") has easy access to
all of the standard sectors of the HDD.

But I think I recall reading about some software that does some kind
of special accesses of the disk drive, say to write to sector "#" and
then tell the disk to mark that sector bad and use one of the spare
sectors in it's place.  Something tricky like that that OS code
doesn't know how do without a custom driver that understands very
low-level HDD control.  Of course, if their software can undo it,
anyone's could, but not if you don't know how, or maybe they've
managed to pick the sectors cryptographically or something, making the
job really tough.

I've also heard of copy protection moving heads half a cylinder and
storing data "between" normal tracks, but that was probably on
floppies; HDD tracks probably almost overlap as it is.

> 2.  Any way the same thing could be done under FreeBSD?

Of course, but here's no code to do it now, AFAIK.


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